Copper foil with an epoxy resin is known as metal foil having a thermosetting resin film. However, when such a conventional metal foil with resin is applied to production of a multilayered wiring board (sequentially multilayered wiring board) by a so-called lamination build-up process in which sheets of metal foil with resin are sequentially laminated, it has been difficult to even the film thickness of the thermosetting resin, which functions as an electrical insulator, all over the wiring board thereby to make the characteristic impedance of the wiring fall within a given range. Further, as the thermosetting resin is not intended to be applied to high-speed circuits or high-frequency analog circuits, the dielectric characteristics and heat resistance of the thermosetting resin are insufficient for such uses. In the conventional metal foil having an epoxy resin used in the production of copper-clad laminates, the dielectric constant of the resin is 3.6 to 3.9, and the glass transition temperature of the cured resin is as low as 120 to 150.degree. C.
In the field of electric wiring boards, it is a matter of urgency to establish a lamination build-up process that will form denser wiring than a through-hole plating process. However, there has not been a suitable resin-having metal foil for use in multilayered wiring board that can be used in high-speed digital circuits and high-frequency analog circuits. It is an object of the present invention to provide a multilayered wiring board which can be used for high-speed digital circuits and high-frequency analog circuits and an electronic device using the same, in which metal foil having provided on one side thereof a film of a thermosetting resin is used, the thermosetting resin having a specific resin flow, a specific relative dielectric constant, and a specific glass transition temperature after curing.